1. Field of the Invention
The invention relates to a device for connecting and locking two building boards, in particular floor panels, on their longitudinal sides and/or transverse sides in the horizontal and vertical direction through an essentially vertical joining movement, wherein the building boards have a top side and an underside, on their lateral edges to be connected to one another are provided with profiles corresponding to one another, and a locking element with a locking projection is provided in the profile of the first building board, which locking element has an inner end and an outer end and is inserted with its inner end in a groove of the first building board, and which interacts with a locking depression provided in the profile of the second building board such that the two building boards are automatically locked in the vertical direction with the joining movement.
2. Discussion of Background Information
A device of this type is known, e.g., from EP 1 415 056 B1 and makes it possible to join two floor panels on their transverse sides. On the longitudinal sides the panels are connected by a tongue and groove profile milled out of the lateral edges. The tongue of the panel to be newly laid is thereby inserted into the groove of a panel already laid and the panel to be newly laid is then pivoted down onto the subfloor. On the transverse side the device makes it possible to simply join the panels by insertion in the vertical direction with a final light pressing in, wherein the locking projection then latches into the locking groove. The locking at the transverse side in the horizontal direction takes place through a hook-shaped profile of the lateral edges, which is milled out of the solid material. In the vertical direction the two panels are locked by the plastic insert that is inserted firmly in the profile of the one building board and has a laterally projecting resilient lip, which latches into an undercut that is made in the profile of the second building board (of the opposite lateral edge).
The connection of the plastic insert to the profile of the first panel is carried out by a web running in the horizontal direction that is inserted into a groove made horizontally in the lateral edge. The locking lip projecting from the locking element is compressed by the panel to be newly laid during the joining movement and springs out again when it overlaps with the undercut. The spring lip must be very elastic so that the automatic engagement occurs securely. The more elastic the embodiment of the spring lip, the lower the forces absorbable by it in the opposite direction (so-called pull-out forces), which act against the joining direction and release the connection. Commercial floor panels have a thickness of 6 to 12 mm. The groove to be made laterally in the profile of the lateral edge, in which groove the plastic insert is attached, must consequently be milled in a width of 2 to 3 mm and a depth of approx. 5 mm. The 1.5 to 3 mm thick plastic insert must then be placed into the groove. Both steps must be carried out at high machine speeds, which is not unproblematic. Through the thickness of the plastic insert, the vertical locking is limited to laminate floors with thicknesses of greater than 10 mm, which further restricts the applicability of the locking system.
When a high elasticity is necessary for the locking, on the one hand the material selection is very restricted, which can lead to increased costs or to increased production expenditure. High spring forces of the locking elements are then necessary if a secure and durable locking is to be ensured. Since this is generally the case with high-quality connections, the forces and deformations generated are usually correspondingly high. For laminate floor panels, a base board of a wood material, in particular HDF or MDF, is used. If high forces act on a laminate, such as HDF, on small areas lengthwise to the layer direction, damage occurs very quickly, in particular in tapered areas. The profile shapings of the profile of the base board can be very stressed by the high spring forces, and chips on the base material occur not infrequently. This can mean that connections do not lock completely or at all. Furthermore, the mostly large deformations of the locking elements often lead to a weakening, in particular when the deformation exceeds the elastic range or the deformation lasts for a longer period. This can lead to reduced restoring forces of the locking elements and thus to only incomplete blocking.